Sharp has developed a prototype direct methanol fuel cell (DMFC) that can output more power for its size than others developed to date, it said Thursday.

This is the first time Sharp has disclosed it is working on DMFCs, so the announcement not only adds Sharp to the growing list of companies chasing the technology, but catapults it past some competitors.

DMFCs produce electricity from a reaction between methanol, water, and air. The only by-products of the reaction are a small amount of water vapor and carbon dioxide, so the fuel cells are typically seen as a much greener form of energy than traditional batteries. A big advantage of DMFCs is that they can be replenished with a new cartridge of methanol in seconds so there's no waiting for a recharge.

Companies like Sharp are keen to use the cells in portable electronics products like music players, laptop computers, and cell phones but there remains a fair amount of development work to be done before the cells replace Lithium-ion batteries as the power source of choice in such products.

The prototype Sharp cell has a power density of 0.3W/cc, which means that it's capable of producing 0.3 Watts of power per cubic centimeter of the power generation part of the cell. Sharp didn't disclose the size of the cell.

The company's goal is the development of fuel cells that offer a longer life than Lithium-ion batteries for the same volume, but it's not clear when they will be available: Work remains to be done and they won't be commercialized soon, a spokeswoman said.

Many other companies are also developing DMFCs.

Toshiba said last week that it plans to begin commercialization of its devices some time this financial year. The company has been promising them "next year" for the last several years but now they are closer at hand, its president said. Competitors including NEC and Sony are also working on the same technology.

Sharp already has a foot in the clean-energy camp as a leading manufacturer of solar energy systems.